AtMAP70-4通过调控微管骨架参与模拟失重影响下胚轴生长的机制研究

Plant is indispensable for the establishment of regenerative life support system in long-term space flight. In condition of weightlessness, normal growth, development, metabolism and other vital movement of plant are affected. Therefore, it is essential to understand the law of plant growth and development under weightlessness environment. In our previous research, we found that, hypocotyl cell growth, organization and dynamics of cortical microtubules and gene expression of AtMAP70-4 were affected by gravity alteration. Based on this, in the project, a newly discovered plant-specific microtubule associated protein AtMAP70-4 is intended to regard as a starting point, and two simulated weightlessness conditions of random positioning machine (RPM) and diamagnetic levitation are employed to research: .(1) the effect of simulated weightlessness on the expression pattern and function of AtMAP70-4 in vitro; (2) the effect of simulated weightlessness on the morphology of plant body and hypocotyl cells, cell elongation rates, organization and dynamics of cortical microtubules, as well as AtMAP70-4 expression patterns in Arabidopsis seedlings with different expression levels of AtMAP70-4..It is in order to clarify the role and the mechanism of AtMAP70-4 by regulating the organization and dynamics of microtubules to involve in hypocotyl growth under the simulated weightlessness condition. The results of this project will help us to comprehend the molecular mechanisms of the organization and dynamics of microtubules affected by weightlessness and then regulating hypocotyl growth, enrich the basic theory of space biology and plant physiology, and provide theoretical and experimental evidence to regenerative life support systems of space and terrestrial crop cultivation and breeding.

植物在中长期空间飞行的可再生生命保障系统中不可缺少。但在失重条件下，植物的生长发育、代谢等生命活动都会受影响。因此，揭示失重环境下植物的生长发育规律至关重要。项目组前期研究发现，重力改变影响下胚轴细胞生长与微管组织动态以及AtMAP70-4基因表达。基于此，本项目拟以新近发现的、植物特有的微管结合蛋白AtMAP70-4为切入点，采用随机回转和抗磁悬浮模拟失重条件研究：（1）模拟失重对AtMAP70-4蛋白体外表达模式及其功能的影响；（2）模拟失重对AtMAP70-4不同表达水平植株的下胚轴细胞形态、伸长速率，微管组织动态，基因表达模式的影响。以期阐明模拟失重条件下，AtMAP70-4通过调控微管组织动态，参与下胚轴生长的作用及机制。本项目研究结果，将有助于深入理解失重影响下胚轴生长的分子机制，丰富空间生物学和植物生理学基础理论，为空间再生生命保障系统和地面农作物栽培育种提供理论和实验依据。

植物在中长期空间飞行的可再生生命保障系统中不可缺少。但在失重条件下，植物的生长发育、代谢等生命活动都会受影响。因此，揭示失重环境下植物的生长发育规律至关重要。项目组前期研究发现，重力改变影响下胚轴细胞生长与微管组织动态以及AtMAP70-4基因表达。基于此，本项目拟以微管结合蛋白AtMAP70-4为切入点，采用随机回转和超重离心模拟失重和超重条件，研究AtMAP70-4蛋白在植物响应重力改变的分子机制。.研究结果显示， AtMAP70-4蛋白在体外能够特异性结合微管，是一种微管结合蛋白，有促进微管成束的作用；在体内，该蛋白主要分布在叶片、种子、根尖等部位，下胚轴中表达量极低；亚细胞定位结果显示其主要位于叶绿体中；重力改变后，包括AtMAP70-4基因在内的大部分基因发生表达下调；同时，重力改变会对AtMAP70-4不同表达水平植株生长和基因表达产生不同影响；不同光照条件下AtMAP70-4蛋白响应重力改变的机制存在差异。以上结果初步表明，微管结合蛋白AtMAP70-4可能参与叶绿体的生命活动过程，同时也是植物响应重力改变的调控因子之一。.本项目研究结果，将有助于深入理解微管结合蛋白的新功能，及其在重力改变下影响植物生长发育的分子机制，丰富空间生物学和植物生理学基础理论，为空间再生生命保障系统和地面农作物栽培育种提供理论和实验依据。